Invasive Plants: Exercise in futility

Here in Florida, many misguided souls spend countless hours (and expend much carbon) in a vain attempt at eradicating so called "exotic/invasive" species. Air potatos, kudzu, pythons, etc. will not vanish, and I for one am glad they are here. This peninsula is now more biodiverse than it has ever been in its entire evolutionary history, one of the few beneficial actions of H. sapiens has been the distribution and introduction of species to new lands. How is it that the only truly "invasive" and damaging species (our own) suffers from such myopia? Should we all dissapear tommorrow, Florida, and the rest of this planet would be far better off thanks to all those introduced evolutionary lineages that have enriched & enhanced communities and will continue to do so well into the future.

Don't agree with some of above, but accept the view of Homo sapiens as an invasive species or at least the major sponsor of invasive species.
Mind you, will come down and stay in Florida this winter. Don't think of myself as personally invasive!

Interesting.
I agree, the loss of homo sapiens, especially many in my new state of FL (no, this was not a destination I'd always wanted to come to, but was where I could afford), would be of no great loss. It's polluted here.

How long do you project the biodiversity to remain so diverse if introduced species replace those that were here?

Introduced species are enhancing the flora/fauna, not replacing. Biodiversity is increasing because of introductions. These introduced species may naturalize, and over time may radiate, speciate, or go extinct. I do not think there is an upper limit to biodiversity, more species is always an improvement.

How is endless acres of kudzu creating biodiversity when it excludes everything else? How about in more northerly states where massive expanses of once-diverse wetlands are completelt taken over by purple loosestrife at the expense of entire communities of fauna and flora?

They had on the national news about 6 weeks ago how the conservation agents were trying to keep the carp out of the Great Lakes. When the boaters go down the Mississippi River the carp literally jump out of the water and land in the boat sometimes hitting the people. It's awful. They call it flying carp.

I imagine you might have a different attitude if YOUR property was rendered useless and devalued by some highly invasive plant. As for:
" if kudzu or purple loosestrife are as damaging and destructive as claimed, then they must have surely caused the extinction of many organisms, although no one can name one."

you need to get around more and see some of the large areas completely taken over by one or the other of the above mentioned plants. You seem to have the idea that these problems are trivial and blown out of proportion by some "tree hugger". Also, I don't know if either of these two plants has caused any extinctions yet, but neither do you. You think everyone in the country competent to speak on the matter has read this obscure thread and failed to respond?

Plants and animals do not destroy, damage, harm, or despoil environments. None of those areas or organisms are "threatened" by introduced species, and "invasive" is a term only used by those lacking an understanding of biological dispersal and the natural movement of species around this planet. Species move, always have, always will.

The real threat to Wood Storks, Snail Kites, etc. are the actions of our species. Compare the acreage of Melaleuca to Citrus in Florida, or the number of Nutria to cows. National Wildlife Refuges only exist because humans have completely dominated and altered all the other areas that Wood storks et al. used to enjoy.

Now you're just being absurd. All the biologists at the US Fish and Wildlife Service lack understanding? Yes, people are responsible for invasive species problems. That doesn't mean it's not a problem. To say the Nutria are contributing to biodiversity in Maryland is utter nonsense.

I've been to Blackwater NWR many times and have never once seen a cow wading in the marshes there. The Nutria are destroying the birds' habitat. People are responsible. It's a problem.

What people (including many biologists) seem to not grasp is that organisms have been moving around this planet for the last three billion years or so, and will continue to disperse/migrate/colonize into new areas as long as there is life on this planet. This global movement of evolutionary lineages is natural, inevitable, and unstoppable, it would be absurd to think otherwise.

There is no difference in the dispersal of organisms, whether it is by wind or wave, bird or bat, monkey or man. Species do not "belong" to some particular area of this earth, there is no such thing as a "native" species, likewise the terms "non-native", "exotic", "alien", and "invasive" have absolutely NO biological meaning whatsoever.

Nutria do in fact contribute to the biodiversity of Maryland; please look up the meaning of the word: biodiversity.
Black Rails are threatened by habitat loss, so yes, people are responsible, its a problem.

While I appreciate your viewpoint, and definitely respect that you are coming from a different direction and introducing a different line of thought, I think you're using terms interchangably that just don't apply.

The term biodiversity applies to an environment with a community of plants, animals and other organisms. As you say, biodiversity is in constant flux for one reason or another, due to natural causes. A native plant that spreads as it normally would throughout its natural environment is not considered invasive in any way. An animal in a state of population explosion (take the lemming for example, whose population flux is legendary) isn't invasive either and contributes to the ever changing populations of its food source and predators.

And again, as you say, the effect man has had on biodiverse environments has been immeasurably, incredibly amazing in many ways. In our profound ignorance, greed and lack of forethought, we have caused irreversable damage to the biosphere. We continue to do so, even though we're overall more aware and more laws are in place to slow our damage down.

To say though, that we have contributed to biodiversity and we should appreciate that is really a faulty view. The introduction of the European starling, English sparrow, and countless other species of plants, insects and so forth have contributed to the REDUCTION of biodiversity in North America. While many species that have been compromised may not be extinct, their numbers are reduced or simply gone from many areas. Man removed nearly every single wolf from the United States; now programs exist to bring them back, but a balance was nearly lost.

In any natural environment, there is a degree of biodiversity, whether it's small and sparse, or lush and profuse. In Florida, the area in which you use as an example, the biodiversity has been compromised for several decades. Yes, some areas are still beautiful and as you say, it's due to the introduced species and actions by people.

BUT...this is not an environment in balance, and cannot truly be seen as a naturally biodiverse environment. If everyone in Florida left today, it would take a very long time for a natural balance to occur. Even then, some of the invasive species would win out, changing what Florida's original, natural environment was into something new. Perhaps some species would become extinct, perhaps some would rebound and thrive, but there's no way to know for sure.

This was my long-winded way of encouraging you not to misuse a term in biology to describe the flourishing flora and fauna in Florida -- yes, I'm sure it's beautiful down there, but you must step back and realize the ultimate changes made by man, no matter how beautiful, are far from a balanced, biodiverse environment.

Biodiversity can be measured. I reject the terms "native","non-native", "exotic", "alien" , because all attempts at defining what is or is not native are predicated on some arbitrary, nebulous, and therefore meaningless time scale. What defines a species as being "native" to North America? Is it pre-Columbian, pre-human, pre-Cambrian? The term "invasive" is just as poorly defined, and is applied to so-called "natives" as well.

Some scientists and others still cling to outdated and unfounded terminology, it can be difficult to have your beliefs and world view challanged, but real scientists will accept the evidence, not the prevailing orthodoxy.

A little education never hurt anyone. Evolutionary history, biogeography, and geology are all fascinating subjects, too bad, they are rarely taught or appreciated.

Before European settlement is the commonly used time frame for defining native plants in North America.

These are the definitions used by the USDA and all federal agencies in the US

Native Plant
A plant that is a part of the balance of nature that has developed over hundreds or thousands of years in a particular region or ecosystem. Note: The word native should always be used with a geographic qualifier (that is, native to New England [for example]). Only plants found in this country before European settlement are considered to be native to the United States.

Invasive Plant
A plant that is both non-native and able to establish on many sites, grow quickly, and spread to the point of disrupting plant communities or ecosystems. Note: From the Presidential Executive Order 13112 (February 1999): 'An invasive species is defined as a species that is 1) non-native (or alien) to the ecosystem under consideration and 2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.' In contrast to item 2) of the Executive Order, which includes plants invasive in agricultural settings, the Connecticut Invasive Plant Working Group lists non-native plants as invasive only if they invade minimally managed (natural) areas.

Non-Native Plant
A plant introduced with human help (intentionally or accidentally) to a new place or new type of habitat where it was not previously found. Note: Not all non-native plants are invasive. In fact, when many non-native plants are introduced to new places, they cannot reproduce or spread readily without continued human help (for example, many ornamental plants).

Naturalized Plant
A non-native plant that does not need human help to reproduce and maintain itself over time in an area where it is not native. Notes: Even though their offspring reproduce and spread naturally (without human help), naturalized plants do not, over time, become native members of the local plant community. Many naturalized plants are found primarily near human-dominated areas; and, sometimes, naturalized is used (confusingly) to refer specifically to naturally reproducing, non-native plants that do not invade areas dominated by native vegetation. However, since invasive plants also reproduce and spread without human help, they also are naturalized – invasives are a small, but troublesome, sub-category of naturalized plants.

Exotic Plant
A plant not native to the continent on which it is now found. (Plants from Europe are exotic in North America; plants from North America are exotic in Japan.)

Translocated Plant
A plant not native to the portion of the continent where it is now found. (California Poppies in New England are an example of a translocated species.)

Opportunistic Native Plant
A native plant that is able to take advantage of disturbance to the soil or existing vegetation to spread quickly and out-compete the other plants on the disturbed site.

Weed
Common Usage - A weed is a plant (native or non-native) that is not valued in the place where it is growing (USDA Animal and Plant Health Inspection Service (APHIS)). Definition - Any plant that poses a major threat to agriculture and/or natural ecosystems within the United States.

Noxious Weed
Common Usage - A plant that is particularly troublesome. Legal Context (Federal Plant Protection Act) - Any plant or plant product that can directly or indirectly injure or cause damage to crops (including nursery stock or plant products), livestock, poultry or other interests of agriculture, irrigation, navigation, the natural resources of the United States, the public health, or the environment. Note: USDA APHIS maintains a list of federally-recognized noxious weeds. It is illegal to import Federally listed noxious weeds or transport them across state lines. Some states or counties maintain lists and have passed laws regarding responsibilities for their control (not applicable in Connecticut). Connecticut laws ban the sale or transport of noxious weed seeds.

Before European settlement is still an arbitrary demarcation, Amerindians surely moved species around as well, many of them were agricultural societies. If one were to use the pre-European settlement argument for the definition of "native", then my banana trees are "native" (Manchester & Kress 1993). Ginkgo is "native" (Mustoe 2002, Scott et al. 1962).

Palm trees are "native" to Alaska, elephants, camels, horses, and cheetahs are also "native" to North America as all of them occured on this continent before the arrival of Europeans.

Pre-European settlement may be arbitrary but it makes sense, to most people anyway.

The extinct Pleistocene mammals referred to aren't the same species (or genera, or even family in the "elephant" example) that exist today. So if an African cheetah were to be introduced into North America, it wouldn't fit the definition of native.

Read the definition again. It hasn't changed. And it's not my definition.

Quoting:Native plants...developed over hundreds or thousands of years in a particular region or ecosystem. Note: The word native should always be used with a geographic qualifier...

What makes you think African cheetahs and the Spaniard's Arabian horses evolved the way their extinct North American counterparts might have? It's like your elephant example; Asian and African elephants already existed at the time mammoths and mastodons roamed parts of North America. They share common ancestry but they're not the same animals.

Yes, the extant cheetahs, elephants, & horses are not the same species that roamed North America. My point was that evolutionary lineages do not "belong" to, or are limited to any one geographic region. Organisms are constantly moving about this planet and will continue to do so regardless of where we think they "belong", or all the futile attempts at stopping such migration. What amazing arrogance humans have, we show up to the party three billion years late and now all other life forms must conform to our idea of what the world is "supposed" to look like.

Louisiana is being overran by none native plants to.Kudzu,nandina,bahia grass,crab gass,burmuda grass,tallow tree,mimosa tree,chamberbitters,wisteria,privet,chinaberry,cogon grass,callery pear,nut sedge just to name a few.English sparrows,starlings and nutria are the worst animals.

I got tired of reading all the "back and forth" debate but I wanted to say that I am 74 yrs old and have seen kudzu ever since I was a little kid in Augusta, GA. It was excellent at stopping the red clay from washing down hills onto the roads (killing people because red mud is "Slippery when Wet". I never saw it overtake vast areas or kill wonderful native plants or ...

The loss of native species through unsuccessful competition is sad isn't it. That's what evolution is all about. (sorry if some of you don't believe in evolution). I think one of the most invasive species around me are all these "native" white tail deer that eat peoples' plants and crash into peoples' cars at night. Wish we had wolves to control the deer but I wouldn't say that if they killed my much loved dog, would I?

I think what I believe is that it's a real complex situation and if you want to be upset, go ahead, but I probably won't believe you are correct.

There is a major flaw in the argument that invasives increase diversity. I am a biologist, and have the joy of teaching undergraduate ecology. One of the first things they learn is that the species diversity of an area takes into account two different factors-- species richness and species evenness. Species richness is the absolute number of species in an area; this is what might increase when invasive species become part of the ecosystem. Species evenness refers to the relative abundance of each species. Let's say you have habitat A, which contains 5 different species, all of which are abundant in the system, and habitat B, which has 5 species as well, but only one species is abundant and the rest are all rare. A biologist would say that while species richness is exactly the same for the two habitats, habitat A has the greater species diversity. The problem with invasives is that while they might increase the absolute number of species in an area, they tend to reduce evenness-- which often causes the system to reach a point where-- from a biologist's perspective-- species diversity is REDUCED.

I've heard the argument many times before that humans are part of the system too, and if plants/animals/etc. get moved around by us it doesn't really matter. Also, people cite that competition is natural, and evolution will eventually determine the winners and losers. The problem is that invasives that are initially brought to an area by humans are given a leg up-- they have suddenly been transplanted to an area where they are no longer held in check by their own predators, the diseases they might have been susceptible to in their home environments, or the competitors that the initially evolved with. Evolution can be fast at times (I have a colleague who has demonstrated extremely rapid evolution in aphids-- much to my dismay), but for the most part, it is a very, very slow process. Plants and animals can't always just adapt to the new situation (the most common fallacy in people's understanding of evolution is that individuals evolve. They don't. Populations do, over time, as changes in the frequency of certain genes occur throughout the population over time). Because invasives have the opportunity to reproduce at will, without being checked by the same processes that would check all the other species in the area, they have an unfair advantage, that I would argue is not particularly natural.

Next, about invasives not driving anything else extinct: I beg to differ. The invasive brown tree snake has been credited with driving 11 bird species in Guam to extinction. Likewise, Hawaiian birds are being decimated by mosquitoes which carry avian malaria & pox, feral cats, and mongooses, all of which were brought over accidentally or intentionally by humans. Some species are down to fewer than 10 remaining individuals, and are not expected to recover. Island species are particularly at risk from invasive species because they have evolved in isolation for so long. Ever wonder why so many island birds are flightless and nest on the ground? There were no rats or mongooses or snakes or cats on the islands! It takes a long, long time for evolution to result in birds that have useless wings. Maybe the island birds that became flightless over time will eventually achieve flight again, but will they do it before being wiped out by invasive predators that themselves have no predators on the islands? Unlikely.

In other systems, invasives are changing the dynamics of the system in a way that natives aren't particularly capable of dealing with. Again, evolution may happen over time, but it might not occur at a fast enough to keep pace with ecosystem change. An example-- invasive grasses in southern California are changing the fire regime. The native plants of the coastal sage scrub ecosystem evolved in a system where small patchy fires occurred about once every 30 years. The fires were relatively small and patchy because the habitat was primarily shrubs that had bare ground between them, which was not conducive to the spread of fire. Now, the areas between shrubs are filled with grasses. Fires are much larger and more frequent. The native shrubs are adapted to infrequent fires (they can crown sprout after low intensity fires), but not to frequent, high intensity fires. It's a positive feedback loop-- the grasses invade, result in more fire, killing shrubs and allowing more grasses to grow, thereby increasing the fire risk even more. Furthermore, until they burn, the grasses create ever growing layers of litter (the decaying plant material kind). Plants that evolved in conjunction with these grasses can germinate underneath these layers of litter-- the SoCal plants, which evolved in a system where the ground was bare, cannot germinate under all this litter. So, have the native coastal sage scrub plants been driven extinct? No, not yet. But they have certainly drastically declined in abundance. The hills near my home were previously coastal sage scrub, but are now primarily exotic grasslands, with exotic mustard thrown in too. I could count on one hand the number of California poppy plants or lupines that I find blooming on those hills each year; people who have lived in the area for 20 years or more can talk about when those hills used to be awash in purple and orange each spring. And again-- going back to the diversity thing . . . we have our students work on small experimental plots in these hills. All they do is rake away the litter left by the invasive grasses. Average species richness for the raked plots? 8 species. Average richness for the litter plots? 1 species.

OK, that was a long rant. I could keep going and going, but I need to go fix some breakfast ;-) This thread started with a post from Florida-- feel free to ask me about my time in Florida, working with the endangered Red-cockaded Woodpecker. I could tell you all about how the stands of invasive melaleuca are affecting it.

Well, this is a very interesting discussion. Much to think about from all points of view. I don't know if the hoarhound that I have
been engaged in battle with is a native to Arizona or not. I do know that the area beneath the oak trees where it was flourishing is showing a lot more diversity in plants than it was when covered with hoarhound. And my cats and I can walk through there without getting full of hoarhound seeds. In the greater plan of the universe I'm sure my puny efforts don't even count. And I'm ok with that. Thanks to all of you for an informative and interesting discussion.

What flabotany conveniently leaves out is all the geologic, hydrologic, and climatic changes that occurred alongside the faunal natural history milestones recounted - because that likely upsets the applecart constructed.

Little things like meteorite impacts, earthquakes, volcanic eruptions, glaciers advancing and receding, etc. play more than a small role in the incidence (or not) of many of the plant and animal life populations listed.

Conveniently and completely avoided are all the points laid out by fritchie21. Well played.

Many years ago I saw a photo in National Geographic of the fence constructed across Australia to try to stop the spread of the jackrabbits introduced for sport. Taken from a low-flying plane, on one side of the fence was a verdant landscape with diverse flora. On the other side of the fence was bare soil as far as the eye could see, right up to the fence. Flabotany would have us believe that he considers the barren landscape as the more diverse one because of the addition of the jackrabbit, which absurd. He otherwise appears to be intelligent and lucid, so I propose we assume he is playing Devil's Advocate and simply trying to stir folks up. If we don't rise to the bait periodically, this thread would stay mercifully dormant. As they said back in the 60's: "What if they held a war and nobody came?"

Well, being stirred up occasionally helps me to look at things a bit more carefully, study a bit, consider several angles, and make up my mind about how I feel about whatever the subject may be. In other words, it makes me think. Anything that makes me think is a good thing. I think...

Just found this thread. Very interesting. I took a lot biology in college and enjoyed it immensely. Ecology and mans' role in mucking up environments always was interesting and distressing to me. And it continues to be. We (people in general) continue to sabotage the most precious and valuable thing we have, the Earth.
fritchie, I very much enjoyed your input. Things are always more complex than lay people realize. The more you study the more you realize how little you know.
I am a long time supporter of The Nature Conservancy.
luciee, I hope your winking face after the bible quote means you don't take it seriously.
I don't have anything profound to say but I really enjoy everyones input here. Well almost everyone!

Well, I just spent three thousand dollars to have two giant truckloads of hedera helix (English ivy) removed from my backyard. This invasive monster plant literally strangles trees to death, and has roots so thick that it is impossible to clear any area to plant anything else. Even if you use a chain saw to remove the roots, the ivy grows right back and kills anything else in the ground. In addition, the ivy serves as a cozy home for Norway rats. It chokes out the plants that are native to Southern California, where I live, and also chokes out any desirable garden plants that one might want to import into one's yard. In short, it chokes out everything. The rats, of course, outcompete other local mammals for food and living space. I can't see any advantage in leaving this situation alone to get worse and worse, with the idea that there is no such thing as an invasive species. Neither English ivy nor the Norway rat belong in Southern California, and there is nothing positive about either one of them.

ditto on that frost weed. Hooray for veeneck and ivy pulling.
Here in Atlanta ivy and rats are abundant and a mess. I pull ivy in my yard regularily but with 3 neighboring yards mostly ivy its an ongoing battle. At least most of the ivy in my yard comes in from the edges so if I pull it up regularily it won't strangle my yard. And I am happy to report an increase in the local RedTail Hawks and owls have put a big dent in the rats. Coyotes help too.

I enjoyed flabotany and the others' conversations a lot.
It is interesting to me that the secondary effects of many imports are so hard to evaluate. When the Europeans (Spanish or others) brought some vegetation to FL, there is no telling what biological advantages or disadvantages were conferred upon some of the native plants and animals. Perhaps for some of the imports there were no advantages but for others there were major ones. After 500 years, the changes are hard to evaluate. In 200 years it will be difficult for our successors to evaluate the bad (maybe good) for which the maleluca, Australian pine, kudzu, et.al. have been responsible.

The obliteration of vast acreages of diverse flora in the South by kudzu along with the myriad fauna species supported by these displaced plant communities isn't too difficult to evaluate. Neither is the desertification of a major portion of the continent of Australia by the introduction of jackrabbits. The wholesale loss of species diversity to a single introduced species is not very charming in the real world. It is little different from paving an entire countryside and suggesting that it is beneficial to nature. Introduction of exotic species and other human activities have rendered a stunning percentage of the planet unable to sustain agriculture. If too little of the environment is degraded in this way even you and I won't eat. What will be the grand advantage to the many species, and nature in general, by their being eliminated by the pythons introduced into the Everglades? Flabotany enjoys playing devil's advocate. One has to either be unaware of, or ignore, thousands of years of documented human modification of the world to buy it.

in response to flabotony's review of north american history,ibelieve one species has been left out ,one of which after the influx of european
settlers, was displaced and almost virtually erradicated. I suppose one
would refer to this as biodiversity.

georgiacat wrote: in response to flabotony's review of north american history,ibelieve one species has been left out ,one of which after the influx of european
settlers, was displaced and almost virtually erradicated. I suppose one
would refer to this as biodiversity.